Re: kern/59783: Can't mount the "special" SGI volume formatted cd9660

["Adrian Chadd via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/59783; it has been noted by GNATS.

From: Adrian Chadd <adrian%freebsd.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/59783: Can't mount the "special" SGI volume formatted cd9660
Date: Sat, 22 Nov 2025 12:05:57 -0800

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 On Sat, 22 Nov 2025 at 10:05, Izumi Tsutsui via gnats <
 gnats-admin%netbsd.org@localhost> wrote:
 
 >
 >  This is because the CD-ROM image for sgimips includes
 >  teh SGI volume header before ISO9660 (for its ARC BIOS)
 >  and it has certain offset (more than 32KB for usual ISO9660).
 >
 >  In most case ISO9660 images don't include explicit disklabel
 >  (i.e. raw struct cpu_disklabel) data in the disk image
 >  and it should be handled by MD disklabel routines.
 >  However most ports assume ISO9660 has no such offset.
 >
 >  > >Fix:
 >  > from mlelstv on irc; I've tested this and it fixes it.
 >
 >  IIRC one annoying issue is sector size on ISO (usually 2048).
 >  If we are trying to offset in actual disklabel, we have
 >  to check carefully all values are consistent (in 512 bytes
 >  or 2048 bytes etc).
 >
 >
 Yeah it's a bit of a minefield, that's for sure.
 
 it's just that the installer can't mount its own CD-ROM image to install,
 and i would like to fix that!
 
 
 
 -adrian
 
 
 >  Thanks,
 >  ---
 >  Izumi Tsutsui
 >
 >
 
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 <div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote g=
 mail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">On Sat, 22 Nov =
 2025 at 10:05, Izumi Tsutsui via gnats &lt;<a href=3D"mailto:gnats-admin@ne=
 tbsd.org">gnats-admin%netbsd.org@localhost</a>&gt; wrote:<br></div><blockquote class=
 =3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
 b(204,204,204);padding-left:1ex">
 <br>
 =C2=A0This is because the CD-ROM image for sgimips includes<br>
 =C2=A0teh SGI volume header before ISO9660 (for its ARC BIOS)<br>
 =C2=A0and it has certain offset (more than 32KB for usual ISO9660).<br>
 <br>
 =C2=A0In most case ISO9660 images don&#39;t include explicit disklabel<br>
 =C2=A0(i.e. raw struct cpu_disklabel) data in the disk image<br>
 =C2=A0and it should be handled by MD disklabel routines.<br>
 =C2=A0However most ports assume ISO9660 has no such offset.<br>
 <br>
 =C2=A0&gt; &gt;Fix:<br>
 =C2=A0&gt; from mlelstv on irc; I&#39;ve tested this and it fixes it.<br>
 <br>
 =C2=A0IIRC one annoying issue is sector size on ISO (usually 2048).<br>
 =C2=A0If we are trying to offset in actual disklabel, we have<br>
 =C2=A0to check carefully all values are consistent (in 512 bytes<br>
 =C2=A0or 2048 bytes etc).<br>
 <br></blockquote><div><br></div><div>Yeah it&#39;s a bit of a minefield, th=
 at&#39;s for sure.</div><div><br></div><div>it&#39;s just that the installe=
 r can&#39;t mount=C2=A0its own CD-ROM image to install, and i would like to=
  fix that!</div><div><br></div><div><br></div><div><br></div><div>-adrian</=
 div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"margin:0px =
 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
 =C2=A0Thanks,<br>
 =C2=A0---<br>
 =C2=A0Izumi Tsutsui<br>
 <br>
 </blockquote></div></div>
 
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